Geological Studies And Reserve Evaluation Of Jiyuan Block In Dingbian Oil Field

Jiyuan oilfield, Dingbian, in the central and western Yi-Shan slope,Ordos Basin, close to the TianHuan depression, experienced a similar tectonic evolution of Ordos Basin. The structural form of oil region as a nearly east-west plunging flat monoclinic, dip less than1degree. Lithology differential compaction local formation of axial northeast-southwest, or nearly what the distribution of multi-slice structural nose. Nose structure for oil and gas enrichment is important.Stratum drilled in Jiyuan oilfield, Dingbian, from top to bottom:the Quaternary, Cretaceous Zhidan group; lower Jurassic system stability group; Zhiluo, Yan’an group; Triassic Yanchang (not to wear). Triassic Yanchang Chang2, Chang6, the extension of the Jurassic Yan’an Yan9area the main purpose of exploration and development Department. Basin has experienced the formation of the lake basin, the development of its peak to shrink, the demise of the entire stage, the formation of multi-sets of students, reservoir, cap combination, constitute the basic geological conditions of hydrocarbon accumulation. Late Triassic Jiyuan area northeast of depositional systems experienced the formation of the lake basin, the development of its peak to shrink, the demise of the entire stage, the development of an inland lake-Delta clastic depositional systems, the formation of multi-sets of students reservoir, cap combination, constitute the basic geological conditions of hydrocarbon accumulation. Yan9and its subsequent deposition, development of a set of fine-grained sandstone, and the flood plains of rivers and lakes of sand and shale facies. Mesozoic Yan’an Formation in the study area and Yanchang reservoir properties, mercury, cast thin section data analysis showed that the reservoir can be divided into four types, of which the Yan9reservoir for Class I is hole permeability, pore structure combination type for the throat, good reservoir properties; Chang2reservoir of Class II, ie porosity and low permeability reservoirs, pore throat combination type thin throat; Chang6evaluation of class Ⅲ with low porosity and low permeability reservoirs pore throat combination type-based thin throat. The study area of Yan’an,2wells block Yanchang reservoir traps are constructed-lithologic traps. Updip of the various traps rely on the sandstone phase transition or pinch out to block oil and gas formation lithology, down-dip direction of tectonic control, see the edge of water or bottom water, oil moisture differences better, have a uniform oil-water interface, thus, are typical elastic water drive structure-lithologic traps reservoir. Chang6reservoir heterogeneity, reservoir subject to strict control of sedimentary facies and reservoir properties are typical lithologic reservoirs. Interdistributary bay muddy sediments, the main abrasive belt on both sides gradually phase into the formation of lateral block the formation of traps updip direction of sandstone pinchout or tight lithology, reservoir distribution morphology and the main sandstone belt, the oil layer thickness strict extent by the sandstone and material control.